how show error if no args was set in console trying execute python script

Question

I need to write python script which need command arguments for executing. I have such code:

try:
    opts, args = getopt.getopt(argv,"htt:tf:d:",["from=","to=","on="])
except getopt.GetoptError:
    print 'logReader.py -f <from> -t <to> -d <on>'
    sys.exit(2)
for opt, arg in opts:
    if opt == '-h':
        print 'logReader.py -f <from> -t <to> -d <on>'
        sys.exit()
    # elif opt
    elif opt in ("-f", "--from"):
        fromTime = arg
    elif opt in ("-t", "--to"):
        toTime = arg
    elif opt in ("-d", "--on"):
        onDate = arg  

But than I run my script without any arguments it just do nothing. How can I add some check like if no args are specified the error message should be shown in the console (or help)

Answer 1

With no arguments set, opts will be an empty list:

if not opts:
    print 'logReader.py -f <from> -t <to> -d <on>'
    sys.exit(2)

You should really consider using the argparse module instead, which lets you specify that some command line options are mandatory.